A027083 a(n) = A027082(n, n+2).

2, 6, 14, 28, 54, 102, 190, 352, 650, 1198, 2206, 4060, 7470, 13742, 25278, 46496, 85522, 157302, 289326, 532156, 978790, 1800278, 3311230, 6090304, 11201818, 20603358, 37895486, 69700668, 128199518, 235795678, 433695870

Offset: 2

Author

Clark Kimberling

Keywords

• nonn
• easy

Links

• Paolo Xausa, Table of n, a(n) for n = 2..1000
• Index entries for linear recurrences with constant coefficients, signature (2,0,0,-1).

Crossrefs

Cf. A008937, A027024, A027082.

Programs

Mathematica

LinearRecurrence[{2, 0, 0, -1}, {2, 6, 14, 28}, 50] (* Paolo Xausa, Sep 16 2024 *)

Formula

G.f.: (2x^2(1+x+x^2))/((1-x)(1-x-x^2-x^3)). Cf. A008937.

a(n) = A027024(n) + 1.

a(n) = A000213(n+3) -3. - R. J. Mathar, Jun 24 2020